This invention relates to forged articles made from metal powders. More specifically, the forged articles are forged engine connecting rods with a forged in bushing.
The connecting rod manufacturing process involves pressure molding metal particles in a closed mold under significant pressure to produce a green compact form of the rod. Next, the green compact is heated in a furnace sufficiently to form a sintered preform in which metal particles are bonded. Next, the sintered preform is hot forged to final rod shape which increases the rod""s density and strength.
The automobile industry continues to challenge connecting rod manufacturers to improve these articles. In many piston powered units, such as compressors and internal combustion engines, full floating piston or wrist pins are used to operatively connect connecting rods with pistons for operating in an associated cylinder. These pins fit into a pin bearing or bushing at the small end of the connecting rod through which the pin extends. Currently, the bushing assembly is realized by pressing in the bushing in a machined forged connecting rod through a separate operation.
In the forged articles or connecting rods of this invention the bushing is assembled during the forging operation of the powder metal article. This reduces the number of manufacturing operations required to process a powder metal article. The main components of this article are a sintered powder metal preform and preferably a bronze bushing. The bronze bushing is inserted in the pin bore of the sintered preform of an article and thereafter forged in during forging. This provides a rough forged article with a forged in bushing that is bonded to the base material. This allows the machining operation to immediately prepare the article for final assembly, thus eliminating the need for the rough boring and pressing operation.
During the forging operation a bushing is inserted into an article such as a connecting rod. The rod is then heated and controlled cooled to allow the bonding of the bushing material to the base material of the rod. One advantage is that the bearing (bushing) push out force is greater than the push out force of the standard interference fit. The insertion also eliminates machining operations and reduces the total cost of manufacturing.